The present disclosure relates to a gas turbine engine, and more particularly to a turbofan engine having a variable area fan nozzle (VAFN) which mitigates acoustic response to reduce total effective perceived noise level (EPNL).
Gas turbine engines which have an engine cycle modulated with a variable area fan nozzle (VAFN) provide a smaller fan nozzle exit area during cruise conditions and a larger fan nozzle exit area during take-off and landing conditions.
The VAFN may generate noise as upstream turbulence interacts with the leading edge of the VAFN.